Test for Valid JSON
Return only JSON even it is string or already JSON
JavaScript
var isValid = true;
var formJson = '{"Title": "Some name", "Data": "No Data"}';
formJson = typeof formJson !== "string" ? JSON.stringify(formJson) : formJson;
try { formJson = JSON.parse(formJson); }
catch (e) { isValid = false; }
if(!isValid) console.log('Invalid JSON data');
else console.log(formJson);